Thanks Blusttoy for the answer!
Another question. I see people talking about buying water slide decals from taobao or samuel decals.
Is there any reason other than ease (?) of application? Or are they actually additional decals not included in the original kit?
As evilerniex explained, waterslide decals are preferred as they are much, much thinner than stickers and have no noticeable edges once dried.
If you topcoat a kit with stickers, you'll notice that the area around the sticker will be slightly frosted (as the topcoat dries over the sticker) and the edges are noticeable. Something like this:
Waterslide decals are also easier to apply once you get the hang of it, because you have a time window to adjust the position of the decals when the surface is slightly moist and it wraps beautifully around curved edges.
Bandai also releases waterslide decals for certain kits and organizations (such as EFSF and Zeon sets).
If you're looking for something else, waterslide decals from third parties, such as Samuel Decals and Keiko, have designs that cannot be officially obtained from Bandai. This allows you to make kits that are from other side- stories [Like changing your GM Sniper to a White Dingo version etc) or to make your own custom unit.
But! The bad thing about waterslide is that, unlike stickers, you need to be careful about using them as they may tear easily. You can fix this by positioning the torn pieces together on the surface, and it will still look good as long as you position it well.
Also, you might want to invest in Decal setters (setters are used to chemically react with the decals to allow them to stick better to the surface and minimize decal edges) or softeners (softeners are usually used to "soften" decals, which may have hardened because of old age, or is thick. It allows decals to wrap around curves better too).
After that, topcoat is the most important to seal the decals and prevent you from accidentally scratching it off. This also makes waterslide decals better than stickers because stickers have tendency to stop sticking at the edges over time.
One last thing, other than stickers and waterslide decals, there are also dry-transfer decals. It works exactly like temporary tattoos and can often be found with MG kits.